There are 39 topics to cover in Economics, each topic takes about 2 classes to cover but you would have to cover at least 1 per class (each class is 45-60 min). Business takes less class time and more study time as there's a LOT of definitions to learn. Overall I would recommend Economics as it has less of an emphasis on learning and more on understanding the concept, so if you were good at J.C. Business Studies you should be able to cover it in 1 year, but if you're the type of student that can learn a 12-page booklet in 1 night, then go for Business.
However, and I'm not sure if this will suit you but if it does I would definitely recommend it, why not consider a subject like Technology or Engineering? They are much much easier to cover in 1 year. If it's not available in your school, doing it externally is a possibility if you are living in Cork or Dublin. I would definitely recommend considering doing Technology, the paper has a lot of common sense questions that you could probably answer yourself even if you're not the best with computers.
TL;DR Economics if you like to understand stuff, Business if you like to learn stuff, and Technology above both if it's available.

business has a lot of definitions to it but a lot of the questions in the exam talk about the benefits of something for the company. half of the time these questions are just common sense but there is a lot of learning and note taking in this subject. if you were to do business in the one year get the less stress more success book and that might help you out.

Hi, I am in 4th year now and for my leaving cert I am doing OL maths & English, I know I wont get a A so that won't help me to get good points so I decided to do a HL subject outside school, so I am thinking of Economics because when I saw the exam papers it looked pretty easy so I thinking of doing it but studying it by myself! because I couldnt find any teachers and I thought I am able to study it if theres like a lot of definitions and all so Can anyone advise me if I should do it for the leaving cert and if not what other subjects Can I do btw I am doing Biology, Business, Homec, French, Arabic HL and I still need 1 more HL

Do business if u did it in the JC .... It's mostly general knowledge and common sense..... All the definitions can be general and in ur own words instead of in relation to business which is good.... I'm doing it after school in sixth yr and am finding it easy even though I do three sciences and applied maths